[Form] Make FormInterface::add docblock more explicit

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| License       | MIT
| Doc PR        | 

When replacing a child form from within a form event, it's not obvious that you have to use the 'add' method. Though it's minor, this will save somebody a google search.
added lines to exceptions for the trans and transchoice tags
[Twig] removed obsolete conditions on Twig versions
minor #10129 [Form] Make FormInterface::add docblock more explicit (billhance)

This PR was merged into the 2.3 branch.

Discussion
----------

[Form] Make FormInterface::add docblock more explicit

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

When replacing a child form from within a form event, it's not obvious that you have to use the 'add' method. Though it's minor, this will save somebody a google search.

Commits
-------

23216aa [Form] Make FormInterface::add docblock more explicit
minor #10132 Remove obsolete conditions (fabpot)

This PR was merged into the 2.3 branch.

Discussion
----------

Remove obsolete conditions

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

In `composer.json`, Twig version is set to 1.12 as a minimum, so all conditions about earlier Twig versions can be safely removed.

Commits
-------

c3ff76a [Twig] removed obsolete conditions on Twig versions
bug #10131 added lines to exceptions for the trans and transchoice tags (fabpot)

This PR was merged into the 2.3 branch.

Discussion
----------

added lines to exceptions for the trans and transchoice tags

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10120
| License       | MIT
| Doc PR        | n/a

Commits
-------

ee0470d added lines to exceptions for the trans and transchoice tags
[DependencyInjection] Remove unneeded file
Create security.id.xlf
minor #10137 [Security] [Translations] added security.id.xlf  (ucay)

This PR was merged into the 2.3 branch.

Discussion
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[Security] [Translations] added security.id.xlf

added translation for Bahasa Indonesia

| Q             | A
| ------------- | ---
| License       | MIT

Commits
-------

7edb5de Create security.id.xlf
minor #10136 [DependencyInjection] Remove unneeded file (florianv)

This PR was merged into the 2.3 branch.

Discussion
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[DependencyInjection] Remove unneeded file

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

I think the file was moved here by mistake from the fixtures.

Commits
-------

caf1809 [DependencyInjection] Remove unneeded file
allow the TextAreaFormField to be used with valid/invalid HTML
bug #10140 allow the TextAreaFormField to be used with valid/invalid HTML (dawehner)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #10140).

Discussion
----------

allow the TextAreaFormField to be used with valid/invalid HTML

The TextAreaFormField previously used saveXML to get a representation of the child nodes of an textarea.
This works pretty fine on simple text is causes issues in case you have broken HTML, as saveXML
will potentially also break encoding/change the structure.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT

Commits
-------

157a9de allow the TextAreaFormField to be used with valid/invalid HTML
fixed CS
Added Bulgarian translation for security component
minor #10141 [Security] added Bulgarian translation (RoumenDamianoff)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #10141).

Discussion
----------

[Security] added Bulgarian translation

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Commits
-------

8fceeac Added Bulgarian translation for security component
add zh_TW validator translations
minor #10144 [Validator][Translation] add zh_TW validator translations (RickySu)

This PR was merged into the 2.3 branch.

Discussion
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[Validator][Translation] add zh_TW validator translations

add Traditional Chinese validator translations.

Commits
-------

c755e85 add zh_TW validator translations
Added delta for Request comparison

Sometimes, tests are failing because REQUEST_TIME
changes between the creation of the various sub-requests.

By using delta, we allow maximum of second of difference.

Example: https://travis-ci.org/symfony/symfony/jobs/17668158#L511
minor #10143 [Tests] [HttpKernel] Added delta for Request comparison (lavoiesl)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #10143).

Discussion
----------

[Tests] [HttpKernel] Added delta for Request comparison

| Q             | A
| ------------- | ---
| Bug fix?      | yes (in tests only)
| New feature?  | -
| BC breaks?    | -
| Deprecations? | -
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Sometimes, tests are failing because REQUEST_TIME changes between the creation of the various sub-requests.

By using delta, we allow a maximum of one second of difference.
Since this is a shady behaviour, I added minimal explanation as comments

Example: https://travis-ci.org/symfony/symfony/jobs/17668158#L511

Commits
-------

3a67309 [Tests] [HttpKernel] Added delta for Request comparison
[HttpFoundation] fixed typo